In the related art, organic electroluminescence (EL) elements (organic light-emitting diodes (OLEDs)) have been developed as candidates for next generation display technologies.
Organic EL elements are light emitting elements, and light emitting areas thereof are defined by open regions of insulating films referred to as edge covers. Since organic EL elements have extremely thin film thicknesses of 200 nm as a whole, elements cannot be formed in portions with large unevenness such as contact holes configured to join pixel electrodes and circuit wirings. For this reason, there is a problem of an increase in reduction of light emitting areas due to contact holes as definition becomes higher.
Contact holes need to have an external form size of about 10 μm due to a relationship between contact resistances of wirings and pixel electrodes. For this reason, light emitting areas are significantly reduced due to contact holes as the definition of panels becomes higher.
Furthermore, wall surfaces of contact holes are steeply formed. For this reason, when thin film organic EL elements are formed, upper electrodes and lower electrodes of the organic EL elements may be short-circuited and pixel defects may occur without light being emitted in some cases.
Patent Document 1 discloses a technique for preventing a film formation failure of an organic EL element in a contact hole. In Patent Document 1, an insulating body is embedded in an electrode hole above a pixel electrode, a protective section is formed, and then a film made of an organic EL material is formed so that a film formation failure of the organic EL material in the electrode hole can be prevented. Thus, occurrence of electric current concentration caused by short-circuiting of an upper electrode and a lower electrode of the organic EL element can be prevented, and thus light emission failure of the organic EL layer can be prevented.